JP6540805B2 - Braking control device and braking control method - Google Patents

Description

  The present invention relates to a braking control device and method for automatically controlling a main braking device commonly used for braking the host vehicle while traveling and a second braking device used for holding the stopped state of the host vehicle.

  Conventionally, in a driving support system such as adaptive cruise control, control is automatically performed to follow the deceleration and stop of the preceding vehicle by automatically controlling the main braking device, which is a hydraulic brake, and control to shift to stop holding thereafter Has been done. Conventionally, Patent Document 1 is disclosed as a travel control device that automatically controls such a main braking device. Here, when the vehicle is stopped and held, the braking force by the main braking device is limited to a certain period of time, and thereafter control is performed to switch to a second braking device such as a parking brake. This is because the durability of the pump is taken into consideration because the main braking device increases the hydraulic pressure by the pump to exert the braking force.

JP, 2010-95189, A

  However, when switching from the main braking device to the second braking device, the second braking device generally has a structure that only the two rear wheels of the vehicle are braked, so all four wheels are braked by the main braking device Switch to a state where only two wheels are braked. Then, in a situation where it is easy to slip like a road surface with a low coefficient of friction or a road with a steep slope, there is a possibility that the vehicle can not be supported and the stopped state can not be maintained. At this time, even if the alarm is issued to the occupant, the time from when the alarm sounds to when the vehicle starts to slip is too short, and there is a problem that the occupant does not have time to operate the main braking device.

  In particular, when the driver removes the seat belt and opens the door while the vehicle is stopped by the driving support system such as adaptive cruise control, the driving support system is urgently released and the main braking device to the second braking device It is switched urgently. In this case, since the occupant takes a position not suitable for driving by removing the seat belt or opening the door, even if the occupant tries to operate the main braking device in order to stop the vehicle body that has begun to slip I could not secure enough time for it.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and ensures a time for an occupant to operate the main braking device even if the main braking device is switched to the second braking device in a slippery situation It is an object of the present invention to provide a braking control device that can be

  In order to solve the problems described above, a braking control device and method thereof according to one aspect of the present invention predict a slip degree indicating the possibility of the own vehicle slipping, and the own vehicle is stopped and held by the main braking device. When switching from the main braking system to the second braking system. At this time, the timing at which the braking force of the main braking device decreases to a predetermined value or less is delayed as the predicted slip degree increases.

  According to the present invention, even if the main braking system is switched to the second braking system in a slippery situation and the vehicle starts to slip, the timing at which the braking force of the main braking system is reduced is delayed according to the slip degree. Can secure time to operate the main braking device.

FIG. 1 is a block diagram showing the configuration of a braking control system according to a first embodiment of the present invention. FIG. 2 is a view for explaining the arrangement on the vehicle of the braking control system according to the first embodiment of the present invention. FIG. 3 is a view for explaining a prediction method of the slip degree by the braking control device according to the first embodiment of the present invention. FIG. 4 is a view for explaining a prediction method of the slip degree by the braking control device according to the first embodiment of the present invention. FIG. 5 is a flowchart showing the procedure of the braking control process by the braking control device according to the first embodiment of the present invention. FIG. 6 is a view for explaining a method of switching from the main braking device to the second braking device at the normal time by the braking control device according to the first embodiment of the present invention. FIG. 7 is a view for explaining a method of switching from the main braking device to the second braking device in an emergency by the braking control device according to the first embodiment of the present invention. FIG. 8 is a view for explaining a method of switching from the main braking device to the second braking device in an emergency by the braking control device according to the first embodiment of the present invention. FIG. 9 is a view for explaining a method of switching from the main braking device to the second braking device in an emergency by the braking control device according to the modification of the present invention. FIG. 10 is a view for explaining a method of switching from the main braking device to the second braking device in an emergency by the braking control device according to the modification of the present invention. FIG. 11 is a flowchart showing the procedure of the braking control process by the braking control device according to the second embodiment of the present invention. FIG. 12 is a flowchart showing the procedure of the braking control process by the braking control device according to the third embodiment of the present invention.

  Hereinafter, first to third embodiments to which the present invention is applied will be described with reference to the drawings. Throughout the embodiments, the same components are assigned the same reference numerals and detailed explanations thereof will be omitted.

First Embodiment
[Configuration of braking control system]
FIG. 1 is a block diagram showing a configuration of a braking control system provided with a braking control device according to the present embodiment. FIG. 2 is a view showing an arrangement on a vehicle of the braking control system according to the present embodiment. As shown in FIG. 1, the braking control system 1 according to the present embodiment includes a vehicle drive controller 3, an engine controller 5, a wiper operation switch 7, a front camera 9, a communication unit 11, and a GPS receiver 13. Is equipped. The braking control system 1 further includes an acceleration sensor 15, a navigation device 17, a front radar 19, a vehicle speed sensor 21, a brake pedal switch 23, a seat belt sensor 25, and a door sensor 27. The braking control system 1 further includes a driving support controller 29, a main braking device 31, a second braking device 33, a display 35, a speaker 37, and a braking control device 100. The braking control system 1 having such a configuration is mounted on a vehicle, and the mounted vehicle is equipped with a system such as adaptive cruise control that follows a preceding vehicle ahead of the host vehicle.

  The vehicle drive controller 3 includes a system for controlling the drive of the vehicle such as an antilock brake system, a traction control system, and a vehicle dynamics control.

  The engine controller 5 is a controller that controls the engine. There is a switch for selecting the operation mode of the engine near the driver's seat of the vehicle. If the snow mode is selected there, the sudden rotation of the engine is suppressed even if the accelerator pedal is suddenly stepped on a road surface with a low coefficient of friction. It is possible to prevent The state of the engine controller 5 is used to determine whether the road surface has a low coefficient of friction.

  The wiper operating switch 7 operates a wiper for wiping away raindrops and snow adhering to the front window. The state of the wiper operation switch 7 is used to determine whether the road surface has a low coefficient of friction.

  The front camera 9 captures the front of the host vehicle to acquire an image. From the captured image, the inter-vehicle distance and relative speed between the preceding vehicle and the host vehicle are detected, and the slope and slip information displayed on the sign in front and the electric bulletin board are read. These pieces of information are used to determine whether the road surface has a low coefficient of friction or a steep road.

  The communication unit 11 performs transmission and reception of information communication services using road-to-vehicle communication and a cellular phone line. Of the received information, the weather and slip information are used to determine whether the road surface has a low coefficient of friction.

  The GPS receiver 13 receives information on the current time as well as the latitude, longitude, and altitude of the vehicle from satellites. The higher the latitude, the lower the temperature, and the higher the altitude, the lower the temperature. Therefore, it can be used to judge whether the road surface has a low coefficient of friction. Also, it can be judged from the history of altitude information whether it is a slope road or not.

  The acceleration sensor 15 measures the acceleration applied to the host vehicle. In the stationary state, the inclination of the vehicle can be detected by measuring the component of the gravitational acceleration. Thereby, it can be judged whether it is a slope road.

  The navigation device 17 electronically stores map information and calculates a guidance route to a destination of the vehicle. It also stores road slope information.

  The forward radar 19 measures the inter-vehicle distance and the relative velocity between the preceding vehicle and the own vehicle using millimeter waves. The vehicle speed sensor 21 measures the vehicle speed of the host vehicle. The brake pedal switch 23 detects whether or not the brake pedal is depressed. The seat belt sensor 25 detects whether the seat belt is fastened. The door sensor 27 detects the open / close state of the door.

  The driving support controller 29 controls a driving support system such as adaptive cruise control, emergency braking, auto hold brake, and an automatic driving system. Furthermore, the system may be provided with a steering control function added to the adaptive cruise control. The driving support controller 29 measures the presence or absence of a preceding vehicle and the inter-vehicle distance using the front camera 9 and the front radar 19, sends a command to the engine controller 5 and the braking control device 100, and accelerates and decelerates the own vehicle. When the preceding vehicle stops, the own vehicle is also stopped to perform stop holding control. The driving support controller 29 performs vehicle speed control for keeping the set vehicle speed constant when there is no preceding vehicle, and maintains distance control for keeping the distance between the preceding vehicle constant when there is a preceding vehicle. Do.

  The main braking device 31 is a brake that is commonly used to brake the host vehicle while traveling, and in conjunction with the brake pedal, the hydraulic pressure (brake hydraulic pressure) is increased by a pump and the brake pad is pressed against the brake rotor to brake the host vehicle. . The main braking device 31 is configured to apply braking to the four wheels of the host vehicle.

  The second braking device 33 is a brake used for holding the stopped state of the vehicle, such as a side brake and a parking brake, and is configured to apply braking to two rear wheels of the vehicle.

  The display 35 also has a function of displaying system states such as adaptive cruise control, emergency brake, auto hold brake, etc., and displaying the operating state of the second braking device 33. The speaker 37 outputs a sound in synchronization with the display at the time of information presentation or warning from adaptive cruise control, emergency brake, auto hold brake or the like.

  The braking control device 100 is a controller that receives an instruction from the driving support controller 29 and automatically controls the main braking device 31 and the second braking device 33 to perform braking control of the vehicle. In this embodiment, it is integrated with the vehicle drive controller 3 and mounted on the vehicle. The brake control device 100 performs stop and hold control by operating the main brake device 31 in accordance with commands from adaptive cruise control, emergency brake, and auto hold brake. Then, when the time limit of stop holding control is exceeded, the main braking device 31 is switched to the second braking device 33 to release the main braking device 31. However, if the seat belt on the driver's seat is removed or the door is opened and the emergency release condition is detected even within the time limit of stop holding control, the main braking device 31 is switched to the second braking device 33 Thus, the main braking device 31 is released. The braking control device 100 having such a function includes a slip degree predicting unit 110 and a braking device switching unit 120.

The slip degree prediction unit 110 predicts a slip degree that indicates the possibility of the host vehicle slipping. The degree of slip increases as the possibility of slipping increases, as described below. The slip degree prediction unit 110 calculates a friction coefficient prediction degree that predicts a friction coefficient of a road on which the host vehicle travels, calculates a slope prediction degree that predicts a slope on the road that the host vehicle travels, and multiplies these. Predict the degree of slip by That is, slip degree = friction coefficient prediction degree × gradient prediction degree However, the slip degree may be predicted using only the friction coefficient prediction degree or only the slope prediction degree.

First, a method of calculating the degree of friction coefficient prediction will be described. The slip degree prediction unit 110 calculates the friction coefficient prediction degree by adding the score of each condition shown in FIG. 3. That is, coefficient of friction prediction degree = a + b + c + d + e + f + g + h + i + j
It becomes.

  As shown in FIG. 3, the slip degree prediction unit 110 gives a score a when there is an operation history of the system that controls the drive or braking of the own vehicle within a predetermined period in the past. The target system is at least one of an antilock brake system (ABS), a traction control system (TCS), and a vehicle stability control (VSC).

  Further, the slip degree prediction unit 110 gives a score b when the traveling mode of the host vehicle is set to the snow mode, and gives a score c when the wiper of the host vehicle is in operation. Furthermore, the slip degree prediction unit 110 gives a score d according to the road display around the host vehicle. For example, if any one of rainfall information, snowfall information and slip information is posted on a sign or an electronic bulletin board within a predetermined period of time in the past, a score d is given.

  Further, the slip degree prediction unit 110 gives points e and f according to the road environment information around the host vehicle. For example, when weather or slip information of snow or rain is received from the information communication service such as road-to-vehicle communication within the predetermined time in the past, the score e is given and the outside temperature is below the freezing point Is given a score f.

  Furthermore, the slip degree prediction unit 110 gives the current date and time, for example, a score g if the date is a winter season, and gives a score h if the time is after sunset. In addition, as position information of the host vehicle, a score i is given if the latitude of the current position is a predetermined value or more, and a score j is given if the elevation of the current position is a predetermined value or more. The same score may be set for all the scores a to j, or a high score may be set for important conditions.

  Thus, the degree of prediction of the coefficient of friction increases as the coefficient of friction of the road on which the host vehicle travels is predicted to be lower. Therefore, the degree of friction coefficient prediction is used to predict the low degree of friction coefficient of the road on which the host vehicle is traveling.

Next, a method of calculating the gradient prediction degree will be described. The slip degree prediction unit 110 calculates the slope prediction degree by selecting the maximum value from the scores of each condition shown in FIG. 4. In other words, gradient prediction degree = MAX (A, B, C, D)
It becomes.

  As shown in FIG. 4, the slip degree prediction unit 110 gives a score A when the output value of the acceleration in the front-rear direction of the acceleration sensor 15 is equal to or more than a predetermined value. Further, when the distance difference value Δh / Δx (Δh: difference in height, Δx: difference in distance) of the height information of the host vehicle acquired from the GPS receiver 13 is equal to or greater than a predetermined value, the score B is given.

  Furthermore, the slip degree prediction unit 110 gives a score C when the road gradient value of the map information around the host vehicle acquired from the navigation device 17 is equal to or greater than a predetermined value. In addition, a score D is given when the numerical value of the sign indicating the slope in the road display around the host vehicle is equal to or more than a predetermined value. These points A to D are set to different points, and the highest point among the given points is calculated as the gradient prediction degree. However, points A to D may have the same point.

  As described above, the degree of grade prediction becomes larger as the grade of the road on which the host vehicle travels is more largely predicted. Therefore, the grade of gradient prediction is to predict the size of the gradient of the road on which the host vehicle is traveling.

  When the own vehicle is in the stop holding state by the main braking device 31, the braking device switching unit 120 passes the time limit of the stop holding control or when the emergency cancellation condition of the driving support system is satisfied. Control to switch from the second braking device 33 to the second braking device 33. At this time, the braking device switching unit 120 delays the timing at which the braking force of the main braking device 31 decreases to a predetermined value or less, as the slip degree predicted by the slip degree prediction unit 110 increases. Specifically, as a method of delaying the timing at which the braking force of the main braking device 31 decreases, in the present embodiment, the timing at which the lowering of the braking force of the main braking device 31 is started is delayed. As described above, since the timing at which the braking force of the main braking device 31 is reduced is delayed according to the degree of slip, it is possible to secure time for the occupant to operate the main braking device 31 even if the vehicle starts to slip by switching the braking device. it can.

  The braking control device 100 is composed of a microcomputer, a microprocessor, a general-purpose electronic circuit including a CPU, and peripheral devices such as a memory. Then, by executing a specific program, it operates as the slip degree predicting unit 110 and the braking device switching unit 120 described above.

[Procedure of braking control processing]
Next, the procedure of the braking control process by the braking control device 100 according to the present embodiment will be described with reference to the flowchart of FIG.

  As shown in FIG. 5, first, in step S10, when the driver turns on the set switch or the resume switch, the driving support controller 29 operates a driving support system such as adaptive cruise control. When the driving support system is activated, the own vehicle travels while maintaining a certain distance between the preceding vehicle and the following vehicle by the following travel control.

  In step S20, when the preceding vehicle following the vehicle is stopped, the braking control device 100 automatically controls the main braking device 31 to stop the vehicle according to the instruction of the driving support controller 29. At this time, the subject vehicle stops with maintaining a constant inter-vehicle distance with the preceding vehicle. Then, the braking control device 100 operates the stop and hold control to bring the host vehicle into the stop and hold state by the main braking device 31.

  In step S30, the slip degree prediction unit 110 calculates the slip degree. As described above, the slip degree prediction unit 110 calculates the friction coefficient prediction degree by predicting the friction coefficient of the road on which the host vehicle is traveling, using the tables shown in FIGS. The gradient prediction degree which predicted the gradient of is calculated. Then, the slip degree is calculated by multiplying the friction coefficient prediction degree and the gradient prediction degree.

  In step S40, the braking control device 100 determines whether the time from when the stop holding control is activated is within the time limit. The time limit is a time set in consideration of the durability of the pump that increases the hydraulic pressure of the main braking device 31. Then, if the time after the stop hold control is activated is not within the time limit, the process proceeds to step S50, and if it is within the time limit, the process proceeds to step S70.

  In step S50, the braking device switching unit 120 activates the second braking device 33 when the time period after the stop holding control is activated exceeds the time limit. As shown in FIG. 6, when the braking device switching unit 120 detects a switching signal output when the time limit is exceeded, the braking device switching unit 120 operates the second braking device 33 first. When the second braking device 33 is activated, an indicator indicating that the second braking device 33 is activated is lighted on the display 35.

  In step S60, when the second braking device 33 operates, the driving support controller 29 normally releases the driving support system. Along with this, the braking device switching unit 120 switches from the main braking device 31 to the second braking device 33. That is, when the second braking device 33 operates, the braking device switching unit 120 normally releases the automatic control of the main braking device 31 which has been responsible for the stop holding control so far, and quickly releases the hydraulic pressure of the brake to perform control. Reduce the power. Further, when the driving support system is released, a release notification image is displayed on the display 35, and a release notification sound is output from the speaker 37 to notify the driver. Thus, when the main braking device 31 is switched to the second braking device 33, the braking control process according to the present embodiment ends.

  On the other hand, in step S70, the driving support controller 29 determines whether the emergency cancellation condition is satisfied. When the driving support controller 29 detects that the seat belt of the driver's seat is removed by the seat belt sensor 25 or when it detects that the door of the driver's seat is opened by the door sensor 27, the emergency release condition is satisfied. judge. Then, if the emergency release condition is not satisfied, the process returns to step S40, and if the emergency release condition is satisfied, the process proceeds to step S80.

  In step S80, when it is detected that the emergency release condition is satisfied, the braking device switching unit 120 operates the second braking device 33. As shown in FIG. 7, when the braking device switching unit 120 detects a switching signal output when the emergency release condition is satisfied, the braking device switching unit 120 first operates the second braking device 33. When the second braking device 33 is activated, an indicator indicating that the second braking device 33 is activated is lighted on the display 35.

  In step S90, when the second braking device 33 operates, the driving support controller 29 urgently cancels the driving support system. Along with this, the braking device switching unit 120 switches from the main braking device 31 to the second braking device 33. That is, when the second braking device 33 operates, the braking device switching unit 120 urgently cancels the automatic control of the main braking device 31 which has been responsible for the stop holding control so far, and quickly releases the hydraulic pressure of the brake to perform control. Reduce the power. At this time, the braking device switching unit 120 delays the timing at which the braking force of the main braking device 31 decreases to a predetermined value or less, as the degree of slip calculated in step S30 increases.

  First, as shown in FIG. 7B, the slip degree prediction unit 110 classifies the slip degree calculated in step S30 into four levels 1 to 4. The classification method sets three thresholds in advance, and level 1 when the degree of slip is smaller than the smallest threshold, level 2 when the degree of slip is equal to or greater than the smallest threshold, and level 3 when the middle threshold or more. Classify as level 4 if greater than or equal to the large threshold. That is, level 1 is a case where the degree of slip is small and the possibility of the vehicle slipping is low, and level 4 is a case where the degree of slip is large and the possibility of the vehicle slipping is high. However, the number of levels does not have to be limited to four, and may be more or less than four.

  Then, as shown in FIG. 7A, the braking device switching unit 120 delays the timing to start the reduction of the braking force of the main braking device 31 according to the classified level. For example, in the case of level 1, the timing to start the reduction of the braking force becomes W and does not change from the normal time, but when the slip degree becomes large and becomes the level 2, the timing to start the reduction of the braking force is delayed Make it X. Then, when the slip degree further increases to reach levels 3 and 4, the timing to start the reduction of the braking force is further delayed from Y to Z. By delaying the timing at which the braking force of the main braking device 31 starts to fall in this way, the timing at which the braking force of the main braking device 31 falls to a predetermined value or less is delayed. The predetermined value is a value of the braking force of the main braking device 31 when the vehicle starts to slip due to a reduction in braking force, and may be obtained in advance by experiment or simulation, or depending on the degree of slip. It may be set each time. Since the timing at which the braking force of the main braking device 31 decreases is delayed as described above, even if the main braking device 31 is switched from the main braking device 31 to the second braking device 33 on a road with a low coefficient of friction or a steep road, The time for the occupant to operate the main braking device 31 can be secured.

  In addition, the braking device switching unit 120 may set an upper limit value in a time when the braking force of the main braking device 31 falls to a predetermined value or less, and change the upper limit value according to the degree of slip. As shown in FIG. 8 (b), upper limit values are set for the time during which the braking force decreases, for each level according to the slip degree. Then, as shown in FIG. 8A, the braking device switching unit 120 reduces the braking force of the main braking device 31 so as not to exceed this upper limit value. For example, the braking force of the main braking device 31 is reduced so that the upper limit value W is not exceeded at level 1, and the control of the main braking device 31 is not exceeded at levels 2 to 4 so as to not exceed the upper limit values X, Y, and Z, respectively. Reduce the power. By providing the upper limit value in this manner, long-term use of the main braking device 31 can be suppressed, and failure of the main braking device 31 can be reduced.

  At the time of emergency release of the driving support system, a release notification image is displayed on the display 35, and a release notification sound is output from the speaker 37 to notify the driver. Thus, when the main braking device 31 is switched to the second braking device 33, the braking control process according to the present embodiment ends.

[Modification 1]
In the first modification, as shown in FIG. 9A, the timing at which the braking force of the main braking device 31 decreases to a predetermined value or less is delayed by decreasing the speed at which the braking force of the main braking device 31 is reduced. . For example, in the case of level 1, the speed at which the braking force is reduced is W, which is not different from that at the normal time, but when the degree of slip increases and becomes level 2, the speed at which the braking force is reduced becomes slower It becomes X. When the slip degree further increases to reach levels 3 and 4, the speed at which the braking force is reduced becomes slower from Y to Z. As described above, by reducing the speed at which the braking force of the main braking device 31 is reduced, the timing at which the braking force of the main braking device 31 decreases to a predetermined value or less is delayed.

[Modification 2]
In the second modification, as shown in FIG. 10A, the braking force of the main braking device 31 is reduced stepwise to delay the timing at which the braking force of the main braking device 31 falls to a predetermined value or less. For example, in the case of level 1, the braking force is reduced stepwise only once as shown by W, but when the degree of slip becomes large and becomes level 2, the braking force is made twice as shown by X It is decreasing gradually. Then, when the slip degree further increases to reach levels 3 and 4, the braking force is reduced stepwise three times and four times as indicated by Y and Z, respectively. As described above, by gradually reducing the braking force of the main braking device 31, the timing at which the braking force of the main braking device 31 decreases to a predetermined value or less is delayed.

[Effect of First Embodiment]
As described above in detail, in the braking control device 100 according to the present embodiment, when the main braking device 31 is switched to the second braking device 33, the braking force of the main braking device 31 is increased as the degree of slip increases. To delay the timing at which the As a result, even if the main braking device 31 is switched from the main braking device 31 to the second braking device 33 on a road surface having a low coefficient of friction or a road with a steep slope and the own vehicle starts to slip, time for the occupant to operate the main braking device 31 is secured. it can.

  Further, in the braking control device 100 according to the present embodiment, the timing at which the braking force of the main braking device 31 decreases to a predetermined value or less is delayed by delaying the timing at which the reduction of the braking force of the main braking device 31 is started. As a result, there is no need to change the speed at which the hydraulic pressure of the main braking device 31 is released, so there is no need to adjust the hydraulic pressure of the braking fluid, and the timing at which the braking force of the main braking device 31 is reduced easily. It can be delayed.

  Furthermore, in the brake control device 100 according to the present embodiment, the speed at which the braking force of the main braking device 31 is reduced is delayed to delay the timing at which the braking force of the main braking device 31 falls to a predetermined value or less. As a result, the braking force of the main braking device 31 is gradually reduced, so that the occupant can grasp the lowering of the braking force and the main braking device 31 can be easily operated.

  Further, in the braking control device 100 according to the present embodiment, the braking force of the main braking device 31 is reduced stepwise to delay the timing at which the braking force of the main braking device 31 decreases to a predetermined value or less. As a result, the braking force of the main braking device 31 gradually decreases, so that the occupant can grasp the lowering of the braking force, and the main braking device 31 can be easily operated.

  Furthermore, in the braking control device 100 according to the present embodiment, an upper limit value is provided at a time when the braking force of the main braking device 31 falls to a predetermined value or less, and the upper limit value is changed according to the slip degree. Thereby, the long-term use of the main braking device 31 can be suppressed, and the failure of the main braking device 31 can be reduced.

  Further, in the braking control device 100 according to the present embodiment, the degree of slip is predicted from the friction coefficient of the road on which the host vehicle travels. As a result, when switching from the main braking device 31 to the second braking device 33 on a road surface with a low coefficient of friction, it is possible to reliably predict that the vehicle slips and starts moving.

  Furthermore, the braking control device 100 according to the present embodiment predicts the slip degree from the slope of the road on which the host vehicle travels. Thereby, when switching from the main braking device 31 to the second braking device 33 on a steep road, it is possible to reliably predict that the vehicle slips and starts moving.

Second Embodiment
Next, a braking control device according to a second embodiment of the present invention will be described with reference to the drawings. In addition, since the structure of the braking control system which concerns on this embodiment is the same as 1st Embodiment, detailed description is abbreviate | omitted.

[Procedure of braking control processing]
The present embodiment is different from the first embodiment in that the braking control process is applied to an emergency brake. The emergency brake determines the possibility of collision with the preceding vehicle based on the distance between the preceding vehicle measured by the front camera 9 and the emergency brake, and determines that the possibility of collision is high. 31 is driven to stop the vehicle. The driving support controller 29 performs stop holding control after the host vehicle is stopped, and issues a command to operate the second braking device 33 to release the main braking device 31 when a predetermined time has elapsed.

  As shown in FIG. 11, in step S110, the driving support controller 29 detects an inter-vehicle distance and a relative velocity with the preceding vehicle based on information from the front camera 9 and the front radar 19 to determine the collision possibility. Here, if the possibility of collision is low, the possibility of collision is continuously determined in step S110, and if the possibility of collision is high, the process proceeds to step S120.

  In step S120, when the driving support controller 29 commands the operation of the emergency brake, the braking control device 100 automatically controls the main braking device 31 to perform deceleration until the host vehicle is stopped. Then, when the host vehicle is stopped, the braking control device 100 operates the stop holding control, and causes the main braking device 31 to put the host vehicle in the stop holding state.

  Hereinafter, in the processes of step S130 to step S190, the same processes as step S30 to step S90 of the first embodiment shown in FIG. 5 are executed. Then, when the emergency brake is normally released in step S160 or the emergency brake is urgently released in step S190 and switched from the main braking device 31 to the second braking device 33, the braking control process according to the present embodiment ends. .

[Effect of Second Embodiment]
As described above in detail, in the braking control device 100 according to the present embodiment, when switching the main braking device 31 to the second braking device 33 even when the emergency brake is activated, the main braking device according to the slip degree 31 Delay the timing at which the braking force decreases. As a result, even if the main braking device 31 is switched from the main braking device 31 to the second braking device 33 on a road surface having a low coefficient of friction or a road with a steep slope and the own vehicle starts to slip, time for the occupant to operate the main braking device 31 is secured. it can.

Third Embodiment
Next, a braking control device according to a third embodiment of the present invention will be described with reference to the drawings. In addition, since the structure of the braking control system which concerns on this embodiment is the same as 1st Embodiment, detailed description is abbreviate | omitted.

[Procedure of braking control processing]
The present embodiment is different from the first embodiment in that the braking control process is applied to an automatic hold brake. The auto hold brake is stopped by driving the main braking device 31 even if the driver does not continue to depress the brake pedal when the driving support system is not operating and the driver is stopping by acceleration / deceleration operation. It carries out retention control. When the accelerator pedal is operated during the stop and hold, the stop and hold control is canceled and the vehicle starts moving.

  As shown in FIG. 12, in step S210, the driving support controller 29 determines whether the driver is stepping on the brake pedal while the host vehicle is in a stopped state, based on the information from the vehicle speed sensor 21 and the brake pedal switch 23. . Here, when the driver does not depress the brake pedal, the state of the brake is continuously determined in step S210, and when the driver depresses the brake pedal, the process proceeds to step S220.

  In step S220, when the operation support controller 29 instructs the operation of the auto hold brake, the braking control device 100 automatically controls the main braking device 31 with a predetermined brake hydraulic pressure to execute stop holding control, and the vehicle Stop and hold.

  Thereafter, in the processes of step S230 to step S290, the same processes as step S30 to step S90 of the first embodiment shown in FIG. 5 are executed. When the auto hold brake is normally released in step S260 or the auto hold brake is urgently released in step S290 and switched from the main braking device 31 to the second braking device 33, the braking control process according to the present embodiment is finish.

[Effect of Third Embodiment]
As described above in detail, in the braking control device 100 according to the present embodiment, when switching the main braking device 31 to the second braking device 33 even when the auto hold brake is activated, the main braking according to the slip degree The timing at which the braking force of the device 31 decreases is delayed. As a result, even if the main braking device 31 is switched from the main braking device 31 to the second braking device 33 on a road surface having a low coefficient of friction or a road with a steep slope and the own vehicle starts to slip, time for the occupant to operate the main braking device 31 is secured. it can.

  The above embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-mentioned embodiment, and even if it is a form other than this embodiment, according to design etc., if it is a range which does not deviate from the technical idea concerning the present invention. Of course, various modifications are possible.

Reference Signs List 1 brake control system 3 vehicle drive controller 5 engine controller 7 wiper operation switch 9 front camera 11 communication unit 13 GPS receiver 15 acceleration sensor 17 navigation device 19 front radar 21 vehicle speed sensor 23 brake pedal switch 25 seat belt sensor 27 door sensor 29 driving support Controller 31 main braking device 33 second braking device 35 display 37 speaker 100 braking control device 110 slip degree prediction unit 120 braking device switching unit

Claims (8)

A main braking device for regular braking of the vehicle during travel to brake the four wheels of the vehicle, said brake the two wheels of the four wheels of the vehicle used to hold the stopped state of the vehicle A braking control device for automatically controlling a second braking device, comprising:
A slip prediction unit that predicts the possibility of the host vehicle slipping;
And a braking device switching unit configured to switch the main braking device to the second braking device when the host vehicle is in the stop holding state by the main braking device.
The braking device switching unit is configured to slip the timing at which the braking force of the main braking device starts to decrease when the slip predicting unit predicts a slip when switching the main braking device to the second braking device. A braking control device characterized in that it is delayed compared to the case where is not predicted . The slip prediction unit predicts the possibility of the own vehicle slipping by the slip degree,
The braking control device according to claim 1, wherein the braking device switching unit delays the timing at which the braking force of the main braking device decreases to a predetermined value or less, as the degree of slip increases.   The braking device switching unit is characterized in that the timing at which the braking force of the main braking device falls to a predetermined value or less is delayed by decreasing the speed at which the braking force of the main braking device is reduced. The braking control device according to claim 1.   The braking device switching unit delays the timing at which the braking force of the main braking device falls to a predetermined value or less by decreasing the braking force of the main braking device in a stepwise manner. Braking control device.   The braking device switching unit sets an upper limit value at a time when the braking force of the main braking device decreases to a predetermined value or less, and the upper limit value is changed according to the slip degree. The braking control device according to any one of the above.   The slip prediction unit predicts the slip degree from the coefficient of friction of the road on which the host vehicle travels, and operates an operation history of a system that controls driving or braking of the host vehicle, a travel mode of the host vehicle, and The slip degree may be predicted based on at least one of an operation state of a wiper, a road display around the host vehicle, road environment information around the host vehicle, a current date and time, and position information of the host vehicle. The braking control device according to any one of claims 2 to 5, wherein   The slip prediction unit predicts the slip degree from the slope of the road on which the host vehicle is traveling, and outputs the acceleration sensor of the host vehicle, altitude information of the host vehicle, map information around the host vehicle, and the host vehicle The braking control device according to any one of claims 2 to 6, wherein the degree of slip is predicted based on at least one of surrounding road indications. A main braking device for regular braking of the vehicle during travel to brake the four wheels of the vehicle, said brake the two wheels of the four wheels of the vehicle used to hold the stopped state of the vehicle A braking control method of a braking control device for automatically controlling a second braking device, comprising:
The braking control device
Predict the possibility of the vehicle slipping;
Switching from the main braking device to the second braking device when the host vehicle is in the stop holding state by the main braking device;
When the main braking device is switched to the second braking device, when slip is predicted, the timing at which the braking force of the main braking device starts to decrease is delayed compared to the case where the slip is not predicted. Braking control method.

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